docs: def _get_fixed_params(im):
      """ Parameters that the user has no influence on. Mostly chosen
      bases on the input images.
      """
      
      p = Parameters()
      
      if not isinstance(im, np.ndarray):
          return p
      
      # Dimension of the inputs
      p.FixedImageDimension = im.ndim
      p.MovingImageDimension = im.ndim
      
      # Always write result, so I can verify
      p.WriteResultImage = True
      
      # How to write the result
      tmp = DTYPE_NP2ITK[im.dtype.name]
      p.ResultImagePixelType = tmp.split('_')[-1].lower()
      p.ResultImageFormat = "mhd"
      
      # Done
      return p